For a use involving communication between a circuit configuration on a primary side (input side) and a circuit configuration on a secondary side (output side) of different power supplies, dV/dt noise has conventionally be caused in some cases resulting from dV/dt to vary a reference potential difference between an input side and an output side of an isolation transformer. In response to the dV/dt noise, effort has been made to prevent malfunction due to such noise.
For example, in a circuit illustrated in Japanese Patent Application Laid-Open No. 2016-46723, a differential voltage responsive to a current flowing on an input side of an isolation transformer is induced in a coil on an output side of the isolation transformer. A potential is received by differential input from the output-side coil to remove the dV/dt noise resulting from dV/dt. In this way, malfunction due to the dV/dt noise is prevented.
According to the aforementioned technique, however, if the dV/dt noise is caused to place a signal at the output-side coil at a voltage going out of an operable range of the output-side circuit configuration, this signal cannot be received by the output-side circuit configuration. Hence, the dV/dt noise cannot be removed even in the circuit to receive a potential by differential input.